Conventional approaches to create biomaterials rely on reverse engineering of biological structures, on biomimicking, and on bioinspiration. Plant nanobionics is a recent approach to engineer new materials combining plant organelles with synthetic nanoparticles to enhance, for example, photosynthesis. Biological structures often outperform man-made materials. For example, higher plants sense temperature changes with high responsivity. However, these properties do not persist after cell death. In this study we permanently stabilize the temperature response of isolated plant cells adding carbon nanotubes (CNTs). Interconnecting cells, we create materials with an effective temperature coefficient of electrical resistance (TCR) ∼2 orders of magnitude higher than the best available sensors.

Ironically, improving the plant cells’ performance as sensors entails killing them. Living tobacco cells, unreinforced by nanotubes, also exhibit a highly sensitive temperature-dependent resistivity. But that response to temperature cycling is transient and reliant on how well the cells retain moisture. They would, as Di Giacomo puts it, “sometimes collapse into dust” above 55 °C, as their water evaporated and they became structurally unstable. Cyberwood, by contrast, tested over an 18-month period, suffered no such deterioration unless heated to much higher temperatures. The nanotubes provide a permanent conductive pathway and substitute for water in the dehydrated material.​​

As the cells grow in a nutrient-filled flask, the thread-like nanotubes partially penetrate (inside the yellow circles) the gelatinous cell and self-assemble into a dense network of intracellular connections. The network lends the composite mechanical strength and electrical conductivity.